ARBOK-Lanthanum (metal case)

Overview

Lanthanum is more abundant in the crust than lead. Its criticality is not geological and not even about price — at $3.18/kg on 3 August 2026 it is one of the cheapest rare earths on the board. The problem is structural: 85–90% of world rare-earth separation sits in China, which also holds 60–70% of lanthanum output, and lanthanum is never mined for itself. It comes out of the ground in fixed proportion with magnet-grade neodymium and praseodymium, so its supply cannot be withheld or expanded without moving NdPr — which means lanthanum availability is decided by a market it does not participate in.

The case ARBOK makes on lanthanum is not scarcity. It is a loss loop that the buyer funds twice.

The FCC double payment. Lanthanum stabilises the zeolite in fluid catalytic cracking catalyst: it holds the structure, extends catalyst life and protects conversion. FCC catalyst is replaced continuously, and the spent load — carrying about 3% lanthanum and cerium oxides — is landfilled. So the refinery buys lanthanum in the fresh catalyst and pays again, weeks later, to bury the same lanthanum. Both payments are made by the same plant, on the same site, in the same month. Roughly 400,000 t/year of spent FCC catalyst is generated worldwide, almost all of it landfilled.

The 2011 precedent, which is the sales argument. When China tightened rare-earth quotas in 2011, lanthanum rose two orders of magnitude. Catalyst manufacturers imposed rare-earth surcharges and refiners moved to low- and zero-rare-earth formulations. The industry did not solve the problem by finding lanthanum; it designed lanthanum out and paid for that in conversion and yield. The consequence has not gone away: refiners today run less lanthanum than is technically optimal because they do not trust the supply — and still discard every kilogram they do use. The buyer has already been burned once and is already paying for the workaround.

ARBOK recovers lanthanum on the Arbok-SA route, in one pass, from two streams that are already liabilities: phosphogypsum, where the rare earths transferred out of the phosphate ore in full, and spent FCC catalyst leachates from the refinery itself.

Applications

FCC catalysts for oil refining — the primary case, and the only one where feedstock and customer are the same site.

Optical glass, where lanthanum raises refractive index without raising dispersion — camera lenses, precision optics.

NiMH battery anodes, where lanthanum is the principal component of the mischmetal hydride alloy.

Auto catalysts and metallurgical additives, alongside cerium from the same concentrate.

Sources: phosphogypsum stacks and fresh phosphogypsum from phosphoric-acid production; spent FCC catalyst leachates from refineries.

Operating Principle

One pass, not two operations. Ground phosphogypsum is dissolved in the acid medium the process itself produces — no reagent is purchased — and the resulting stream is separated by Arbok cold boiling under deep vacuum at ambient temperature. No furnaces, no catalysts, no membranes, no consumable reagents, and therefore no CO₂ from the recovery step.

La, Ce, Nd and Pr are separated into individual oxides in the same pass, inside the solution itself, with only final polishing after it — the cascade of hundreds of stages, where the Chinese separation monopoly actually sits, is not required. Radionuclides report to an immobilised mass of 0.1–0.5% of volume. Spent-catalyst leachates enter the same tract without a separate line.

Lanthanum is not targeted as a solute. It leaves with the rare-earth fraction because the whole stream is separated, which is why its recovery does not carry a cost of its own.

Key Parameters

| Parameter | Value |

|---|---|

| Process | Arbok-SA route: dissolution in own acid medium + vacuum separation |

| Operating pressure | deep vacuum |

| Working temperature | ambient — no heat supplied, no setpoint |

| Dissolution module | modular, scaled by stack volume |

| Radionuclides | immobilised, 0.1–0.5% of volume |

| Mass to commercial product | ~99.5% |

| Consumables | none — no reagent, furnace or membrane |

Resource and market context:

| Parameter | Value |

|---|---|

| Lanthanum price | $3.18/kg, SMM, 3 August 2026; range-bound after an 18.3% move the prior month |

| FCC-grade lanthanum | ~$2.67/kg |

| Share of world REE output | 25–30% by mass, produced in fixed ratio with Nd and Pr |

| China | 60–70% of lanthanum output; 85–90% of world separation |

| Regulatory status | on the EU critical raw materials list |

| Phosphogypsum accumulated | 3.7–6+ billion t; 200–300 Mt/year generated; ~35% utilised |

| Grade in phosphogypsum | REO ~0.3%, of which La and Ce up to 60% — about 1.8 kg La+Ce per tonne |

| Spent FCC catalyst | ~400,000 t/year worldwide, ~3% La and Ce oxides, almost entirely landfilled |

Architecture and Components

Dissolution reactors operating in the process's own acid medium; vacuum cold-boiling separation train; radionuclide immobilisation mode; mixed rare-earth concentrate take-off; compact second-stage oxide separation; acid and water product lines. Modular, and integrable into an existing phosphoric-acid plant or connected to a refinery's spent-catalyst handling.

Advantages

The feedstock is already paid for twice. In the FCC case the refinery buys lanthanum and then pays landfill on the same lanthanum. Recovery removes a purchase and a disposal cost in one move.

No separate operating cost for the metal. The acids and clean water produced in the same pass are the products that carry the process. At about 1.8 kg of La+Ce per tonne of phosphogypsum, roughly $7 of metal, lanthanum would never justify standalone recovery — and does not have to.

Spent catalyst stands on its own. At ~30 kg of La+Ce oxides per tonne, roughly $105 per tonne of spent catalyst, against a landfill fee paid today.

No furnace, no reagent, no CO₂ from the recovery step, and phosphogypsum stacks are eliminated rather than monitored in perpetuity.

Supply outside the separation monopoly, delivered to the same industries — refineries, glassmakers, catalyst producers — that were burned in 2011 and have been designing around the risk ever since.

Integrations

ARBOK-Lanthanum-Cerium · ARBOK-PHOSPHOGYPSUM · ARBOK-SA · ARBOK-Scandium-REE · ARBOK-Neodymium · ARBOK-Praseodymium

This card is the lanthanum-specific case on the route described jointly with cerium in ARBOK-Lanthanum-Cerium. The magnet-grade Nd and Pr fraction of the same concentrate is covered by ARBOK-Neodymium and ARBOK-Praseodymium; gypsum purification by ARBOK-PHOSPHOGYPSUM.

Deployment & Operation

Characterisation of the phosphogypsum stack and of the refinery's spent-catalyst leachate → module sizing against volume → installation at the phosphoric-acid site, at a legacy stack, or at the refinery → commissioning. Operation is continuous at ambient conditions, and capacity is scaled by adding modules rather than by resizing a single train.

TRL

TRL 9. The Arbok-SA route carries a measured product balance recorded in the preprint, and the lanthanum case is a feedstock configuration of that route rather than a new process.

Market Potential

Lanthanum is 25–30% of world rare-earth output by mass, so the volume is not the constraint — the separation step is. The commercially interesting fact is where the metal already sits: the United States alone holds ~1.5 billion t of phosphogypsum, about 1 billion t of it in 25 Florida stacks, growing ~30 Mt/year. The annual US increment alone carries 54,000 t/year of La and Ce, many times domestic consumption.

The FCC channel is smaller in tonnage and much better in economics, because the feedstock is concentrated, delivered by the customer, and currently carries a disposal charge instead of a price.

Buyers are refineries, catalyst manufacturers, optical-glass makers and NiMH producers — all of whom hold a live memory of the 2011 squeeze.

Typical Project Economics

Revenue does not rest on lanthanum. In the phosphogypsum case the acids and clean water produced in the same pass carry the operation, and La and Ce are recovered at no separate operating cost — about $7 per tonne of stack material at current prices. In the FCC case the metal is the case: about $105 per tonne of spent catalyst against a landfill fee the refinery pays today.

Site-level CAPEX and payback: computed per site against stack volume or catalyst turnover.

Risk Factors

The metal is cheap and will stay cheap unless policy moves it. At $3.18/kg lanthanum cannot underwrite a project on its own; every case here depends on the co-products or on the avoided disposal cost.

Fixed co-production. Lanthanum output follows NdPr demand, so a flood of magnet-grade production depresses lanthanum regardless of its own market.

The second stage is the bottleneck and it is not ARBOK's. Splitting the mixed concentrate into individual oxides is exactly the capability concentrated in China; a concentrate without an offtake to a separation plant is not a product.

Demand has been engineered downward. Refiners moved to low- and zero-rare-earth FCC formulations after 2011, so the addressable lanthanum content per tonne of catalyst is lower than the historic figure and varies by refinery.

Feed variability and permitting. Phosphogypsum differs by ore body and by decade of deposition, and its naturally occurring radionuclides carry handling and permitting exposure even when immobilised.

Related Technologies

ARBOK-Lanthanum-Cerium · ARBOK-PHOSPHOGYPSUM · ARBOK-SA · ARBOK-Scandium-REE · ARBOK-Neodymium · ARBOK-Praseodymium · ARBOK-Yttrium